Mercury switch and the like



y 1933- F. s. ARMSTRONG 1,916,957

MERCURY SWITCH AND THE LIKE Filed April 22, 1930 2 Sheets-Sheet l July 4, 1933. F, s. ARMSTRONG MERCURY SWITCH AND THE LIKE 2 sheets-sheet 2 Filed April 22, 1930 Z2 z/arz $7 2 airway 1;

Patented July 4, 1933 A UNITED STATES PATENT OFFICE FRED S. ARMSTRONG, OR RIVER FOREST, ILLINOIS, ASSIGNOR TO JEFFERSON ELECTRIC COMPANY, OF BELL'W'OOD. ILLINOIS, A CORPORATION OF ILLINOIS MERCURY S'WITCH AND THE LIKE Application filed April 22, 1930.

This invention relates to certain improve ments in mercury switches and the like. The invention relates particularly to improvements in the coir-traction and operation of mercury switches, said improvements relating particularly to a construction whereby a thermostatically operated device produced which will operate to automati cally open and close the circuits under thermostatic control. In this connection it is an object to provide a mercury switch arrangement in which the tilting of the switch back and forth into the two positions is performed by the variations of a thermostat under change of temperature.

One object in connection with tho foregoing is to provide a device which will be very sensitive and close in its range of operation,

thereby insuring the operations of the device cury will. flow from one end to the other. Thisback and forth flow of mercury results in a considerable shifting of the position of the center of gravity of the tilting element, such shifting of the center of gravity being back and forth in a direction generally parallel to the length of the device and transversely to the axis of tilt. As a consequence, if the device is nicely balanced when tilted into one position so that it can be easily shifted over the center, the subsequent tilting will result in such a transfer of the center of gravity that the device can not be as easily tilted back again. In other words, the physical balancing on one side of the center when in one position will be followed=hy an unbalancing at the other side of the center when the device is tilted over.

One object of the invention to provide an arrangement for automatically compensating for this shift of center of gravity due to mercury movement so that the device can be tilted back and forth in either directi. m-wi th Serial No. 446,268.

substantially the same amount of accuracy and delicacy of movement in either direction.

More particularly, it is an object to ac- ('OH'IPllSl] the foregoing result by means of an electro magnetic counter balance which comes into operation harmoniously with the tilting and circuit controllin operations, such electro magnetic counter dmlance serving to compensate for the shift of the center of gravity.

In connection with the foregoing, it is a further object to provide an arrangement such that only a Very small amount of current is necessary for controlling the operation of the electro-magnetic counter balance, so that the device will not become overheated and also resulting in a device which is economical to operate and requires only a very small current consumption.

Another object of the invention is to provide an improved construction of mercury cont-actor. In this connection it is an object to provide an arrangement so that the arcs incident to making and breaking the circuit will be very promptly suppressed and con trolled thereby reducing the burning and other deleterious action incident to the operations of the device.

Specifically, it is an object to provide a construction in which the interior of the mercuy cont-actor is placed under a gas pressure considerably greater than atmospheric. Expe-' rience demonstrates that the increase of gas pressure. above atmospheric serves to materially reduce the arcing and serves to substantially suppress the are at the instant the continuity of the mercury connection is broken.

In connection with the foregoing, it is an object to also provide a construction of shell for the contactor, which shell construction is so arranged that the same can not only be readily produced but also is so arranged that it can be readily subjected to the desired gas pressure which can then be sealed into the container. In connection with the foregoing, it is another object to provide a construction such that the chamber can be perfectly sealed without substantial difiiculty and while the gas pressure is maintained therein so that the contactors can he manu factured in quantities and of a. uniformity of product which is essential to a successful manu l'acturing operation. v

In connection with the foregoing, it is also an object to provide a contactor construction of very simple design and one which can be made at low cost and will be very durable and permanent in construction and operation.

Other objects and uses will appear from a detailed description of the invention which consists in the features of construction and combinations of parts hereinafter described and claimed.

In the drawings:

Figure 1 shows a side elevation of the assembled device, the contactor proper being shown in section so as tc show the interior construction thereof, and the device being in the open circuit position;

Figure 2 shows a plan view corresponding to Figure 1;

Figure 3 shows a fragmentary section on the line 33 of Figure 1, looking in the direction of the arrows;

Figure 4 shows diagrammatically another layout in which the thermostatic control includes a counter balancing weight which is carried at the lower end of an arm, the thermostatic member operating to swing said arm back and forth by direct thrust;

Figure 5 shows another view similar to that of Figure 4, with the exception that the counter-balance weight and arm are controlled by a spiral thermostatic element;

Figure 6 shows a view similar to that of Figure 4, with the exception that the thermostatic element is in direct line with the axis of the contactor and the bracket arm has been raised up above the same;

Figure 7 shows a view similar to that of Figure 4, with the exception that the counterbalance weight is controlled by means of a helical thermostatic element;

Figure 8 shows a fragmentary section on the line 88 of Figure 7, looking in the direction of the arrows;

Figure 9 shows a view similar to that of Figure 4 with the exception that use is made of a spiral thermostatic element operating, however, through a diflerent system of arms and links than the arrangement of Figure 5; and

Figure 10 shows diagrammatically an electric circuit including the solenoid 44.

Referring first to Figures 1, 2, and 3, in particular, the contactor element is designated in its entirety by the numeral 10. It

includes a tubular section 11 of iron or othermetal which will not be corroded by mercury, a central sleeve or thimble 12 of insulating material such as lavite or isolantite, and an end plug 13 also of metal such as iron which will not be corroded by the mercury. The tubular section 11 and the end plug 13 are threaded into the central insulating section 12 as shown in Figures 1 and 3. F urthermore, this central section 12. is provided with an inwardly reaching annular lip or flange 14 which preferably reaches somewhat beyond the inner surface of the tubu .lar section 11 and thereby establishes a bridge piece. The plug 13 is preferably slightly socketed as shown at 15 so that the mercury will run intosaid socket and be partially trapped beyond the bridge piece 14 when the device is tilted over towards the right.

The outer end of the tubular section 11 is provided with a threaded plug 16. This plug preferably tapers very slightly so that as it is threaded home, it will Wedge and seal more perfectly. (The amount of taper indicated in Figure 1 is exaggerated) There is a gas passage 17 which leads sidewise or at right angles from the body of the tubular section 11. This passage 17 is fully closed and is perfectly sealed when the plug 16 is threaded up tight as shown in Figure 1; whereas, when the plug is unthreaded partially into the dotted line position of Figure 1, the inner end of the passage 17 is uncovered so that said passage communicates with the interior of the contactor.

The end plug 13 is provided with a longitudinally extending bore 18 which accommodates a machine screw or bolt 19. This bolt when tightened up serves to thoroughcury will run down and past the bridge 14,

so as to establish connection between the tube 11 and the plug 13.

The interior of the contactor is placed under the desired amount'of gas pressure, and preferably hydrogen or some other gas than air is used which will not oxidize the mercury and the contacts. This gas pressure is introduced and produced in the following manner:

The plug 16 is left partially unscrewed into the dotted line position of Figure 1, so

as to expose the passage 17. Incidentally, the contactor should be turned over so that the passage 17 faces upwardly in order to avoid loss of mercury out throng? said passage. The machine screwor bolt 19 is also removed so as to permit the device to be flushed, the device being tilted so that the plug 13 stands at a high enough elevation to prevent the mercury from running out through the-passage 18.

The desired gas is then introduced by connecting the hose to the outer end of the passage 17 and gas is flushed through the device until all of the air has been expelled through the passage 18. The bolt or machine screw in is then threaded into the passage 18 and tightened up. The continued introduction of gas through the passage 17 will build up the desired pressure inside of the contactor. This pressure maybe as heavy as desired, for example. 50400 pounds per square inch or greater. \Vhen the desired pressure has been created. the plug, 16 is screwed down tight, thereby sealing off the inner end of the passage 17 and trapping the pressure which has been built up inside of the device. If desired. the projecting portion of the plug 16 may be sealed by solder or the like 21, and if desired, the outer end of the passage 17 may be plugged by solder or the like so as to prevent any possibility of leakage.

The contaetor 10 is pivoted or swivelled to swing about a horizontal transverse axis. For this purpose the studs 22 and 23 are threaded into the central insulating section 12, said studs passing through bracket arms 24 and 25 which reach upwardly from a base member 26. The studs 22 and 23 are preferably held in place by nuts 27 and 28, but these are not tightened sufficiently to interfere with the flee rocking of the contactor. Preferably, also, washers 29 and 30 are set between the bracket arms 24 and 25 and the adjacent faces of the insulating section 12.

The wires constituting the circuit to be c011- trolled are shown at 31 and 32. They extend through the studs 22 and 23 and the inner ends of said wires are turned over and connected respectively to the plug 13 and to the tubular section 11 as shown in Figure 3. It will be understood that the wires are sealed into the studs 22 and 23 in gas-tight fashion so that the introduction of the wires does not affect the gas-tight condition of the contactor.

Normally the device is so balanced that it stands in the open circuit position of the different figures. For this purpose a. threaded pin 33 is preferably provided as an extension of the plug 16, and an adjustment nut 34 is threaded on to said pin. The nut 34 can be set back and forth in order to bring the device into the proper condition of balance. It will be understood that the body of mercury 20 also assists in tilting the device into the "position of Figure 1.

A thermostatic device is provided for balancing the device and causing itto tilt towards the right in Figure 1, thereby causing the mercury to flow over into the closed circuit position. In the construction of Figures 1 and 2, this thermostatic device includes a series of double elliptic compound bars 35, and 36, and 37 and 38. Each of the bars 39 thereof is compound and tends to bend or deflect under change of temperature. The result is that each bar will either increase its curvature or straighten out, depending upon the rise or fall of the temperature.

The central portions of the doube elliptic devices are fastened together as shown at 40 so that their action is multiplied. A thread- 7 ed pin 41 extends outwards from the last thermostatic element and is PI'OXldQd with a counter balance weight 42 threaded thereon so that this weight can be adjusted in compa rison to the adjustment of the weight 34.-

Preferably a' horizontal stop pin 43 is mounted on the bracket 24, said stop pin underlying the plu 13 of the contactor in position to arrest the tilting movement of the device towards the right during the circuit closing operation.

It will now be understood that as the temperature of the thermostatic elements rises, the counter-weight 42 will be moved farther and farther towards theright until finally the effectiveness thereof bQCOlIlOS sufficient to overbalance the weight 34 and cause the device to tilt towards the right and into the circuit closing position. Thereafter, as the temperature of the device changes in the other direction, the thermostatic elements will straighten out more and more so as to draw the counter-weight 42 towards the left and presently the effectiveness thereof will not be sufficient and the device will tilt back into the position of Figure 1.

It will be noted that between the two extreme positions the mercury has shifted from the position of Figure 1 over to aposition where the mercury is effective on the other side of the center or at any rate does not assist the weight 34 as much as formerly. I have therefore provided a solenoid 44 located on the stand 26 Ma position beneath the tubular element 11. This solenoid is connected in with the circuit to be controlled so that when the device tilts over into the closed circuit position, the solenoid is energized and exerts a magnetic pull on the iron tube 11 assisting in the downward pull thereof. The amount of this assistance is sufficient to counter-balance the change of leverage of the mercury body 20 due to its change of position, so that the device is in a condition of balance when tilted into the closed circuit position as well as formerly.

By the foregoing arrangement the sensitiveness and effectiveness of the device is. greatly enhanced and it can be made to operate within very close limits of temperature change.

Usually. the solenoid 44 will be placed in from the plug 13 of the contactor. A rigid arm 47 extends out from the plug 13 and a downwardly depending arm 48 has its upper end pivoted to the end of the arm 47 at the point 49. The counter-balance 50 is carried by the arm 48; and a pin 51 extends from the thermostatic element to the arm 48, so as to rock the saine back and forth. In this arrangement. the sensitiveness of the device can be increased due to the fact that the movement of the thermostatic element is exaggerated or increased by the presence of the arm 48.

The construction of Figure 6 is-similar to that of Figure 4 with the exception that the thermostatic element is. placed in alignment with the contactor, the bracket arm 46 reaching upwardly and carrying the rigid arm 47 on its upper end. The arm 48 is pivotally connected to the end of the arm 47 by the pin 49 as in the construction of Figure 4.

In the construction of Figure 5, there is a spiral thermostatic element 52 that has one end rigidly connected to an arm 53 reaching out from the plug 13. The other end of the spiral thermostatic element is pivotally connected to the outer end of the arm 53, and is rigidly connected to an arm 54 which reaches downwardly and carries the counter-weight 55 at its lower end. With this type of arrangement the movement of the counterweight 55 may be greatly multiplied by increasing the number of turns of the spiral.

The construction of Figure 9 is similar to that of Figure 5 in the sense that use is made of a spiral thermostatic element 56 having one end rigidly connected to a pin 57 which extends outwards from the plug 13. An arm 58 is pivoted to the outer end of the arm 57 at the point 59 and carries the.counter-weight 60 at its lower end. A link 61 connects the free end of the spiral 56 with the upper end of the arm 58 by a pivotal connection 62. 1

In the construction of the Figures 7 and 8, an arm 63 extends outwardly from the plug 13, an arm 64 being pivotally connected to the outer end of the arm 63, by the pivot pin 65. The lower end of the arm 64 carries a counter weight 66. A helical thermostatic element 67 has its upper end suitably attached to a suitable support 67a; the lower end of the helical-thermostatic element has an arm 68 (see Fig. 8) which reaches outwards and is connected to the upper end of the arm 64 by a linlr 69. It will be understood that the arrangement of Figures 7 and 8 is intended for use where one end of the thermostatic element is anchored to some other stationary device.

Examination particularly of Figure 1 disclosesthe fact that the bridge piece 14 of the insulating section or member 12 stands up slightly above the lowest portion of the socket 15 in the plug 13. As a consequence'thereof,

there is trapped a small body of mercury within the socket of the plug 13 when the device is turned down into the open circuit posit-ion of Figure 1. It therefore follows that the operation of actually opening the circuit tions in which the solenoid 44 is placed in parallel with the output circuit so as to operate according to the disclosures herein explained.

It will be understood that while I have herein shown and described only certain embodiments of the features of my present invention, still I do not intend to limit myself thereto except as I may do so in the claims.

I claim:

1. In a device of the class described, the combination of a mercury contactor includ ing a chamber wherein is contained a body of mercury adapted to be shifted from end to end of the device when it is tilted, means for pivotally supporting the device to permit it to tilt about a horizontal transversely extending axis whereupon the mercury travels lengthwise of the device between circuit closing and circuit opening positions, with consequent shifting of the center of gravity of the device, an adjustable counterbalance on the device for establishing a condition of balance when the mercury is at its position most distant from the pivotal sup- .port, one portion of the device being of magwhen the mercury is in one position where said mercury is closer to the pivotal point of the device than otherwise, to thereby compensate for the shifting of center of gravity of the device due" to shifting of the position of the mercury, substantially as described.

2. In a device of the class described, the combination of a mercury contactor including a chamber wherein is contained a body of mercury adapted to be shifted from end to end of the device when it is tilted, means for supporting the device to permit it to tilt about a horizontal transversely extending axis whereupon the mercury travels lengthwise of the device between circuit closing and circuit opening positions, with consequent shifting of the center of gravity of the device, and means operative only when the device is shifted into the position where the mercury is closest to the axis of tilt for exerting a tilting action on the device in amount and direction substantially equal to the change of tilting action due to shift of the center of gravity aforesaid, whereby the device is in a substantial condition of balance "i in both of its positions of .tilt, substantially as described. a

3. In a device of the class described, the combination of a mercury contactor includ- 5 ing a chamber wherein is contained a body of mercury adapted to be shifted from end to end of the device when it is tilted, means for supporting the device to permit it to tilt about a horizontal transversely extending axis whereupon the mercury travels lengthwise of the device between a circuit closing position in which the mercury is close to said axis and a circuit opening position, in which the mercury is more distant from said axis, with consequent shifting of the center of gravity of the device, electromagnetic means tending to tilt the chamber to the open circuit position, and means for energizing the same when the circuit is closed, whereby the device is in a condition of substantial balance in both of itspositions, substantially as described. h

4. In a device of the class described, the combination of a mercury contactor adapted to be tilted about a horizontal transversely extendin axis, means for supporting the said device to permit such tilting action, a shiftable counterweight on one end of the device adapted to be shifted between positions which are at different distances from the axis aforesaid, and a selfcontained thermostatically operated member connected to said counterweight to shift the same to change the distance of said counterweight from the axis to thereby tilt the'contactor, substantially as described.

5. In a device of the class described, the combination of a mercury contactor adapted to be tilted about a horizontally extending said device to permit such tilting action, a shiftable counterweight'on the device adapted to be shifted between positions which are at different distances from the axis aforesaid, and thermostatically operated means for shifting said counterweight with respect to the axis to thereby affect the balance of the contactor with consequent tilting thereof, substantially as described.

6. In a device ofthe class described, the combination of a mercury contactor adapted to be tilted about a horizontally extending transverse axis, means for supporting the said device to permit such tilting action, the mercury shifting with respect to the axis when thedevice is tilted, a shiftable counterweight on the device adapted to be shifted between positions which are at different distances from the axis aforesaid, thermostatically operated means for shifting the counterweight with respect to the axis to thereby alfect the balance of the contactor with consequent shifting thereof, and means for automatically compensating for the shift of center of gravity ofthe device due to shift transverse axis, means for supporting the p of mercury position with respect the axis combination of a mercury-contactor,- means for supporting the contactor in either of two positions of rest, a counterweight movably connected to the contactor, and thermostatic means on the contactor connected to the counterweight operative effectively to shift the counterweight to move the contactor from either position of rest to the other, substantially as described.

8. In a device of the class described the combination ofa mercury contactor, means for supporting the contactor in either of two positionsof rest, a counterweight movably connected to the contactor, and thermostatic means connectedto the counterweight operative effectively to shift the counterweight to move the contactor from either position of rest to the other, substantially as described.

9. An electric contactor comprising in combination a container, means for mounting the same to tilt about a horizontalaxis extending'transversely of the container, a body of mercury within the container, a counterweight tending to tilt the container into one position, and a seriesof elliptical bimetallic thermostatic devices having their central portions connected together into a series, the central portion of one end of said series bemg connected to the container, and a counter I weight connected to the central portion of the other end ofssaid series, whereby changes of temperature result in a multiple expansion or contraction of said series of elliptical thermostatic devices to thereby cause accumulative movement of said last named counterweight, substantially as described.

10. An electric contactor comprising in combination a container, means for ,pivotallymounting the same for tilting movement about a horizontal transversely extending axis, a body of mercury within said container adapted to make and break the circuit when the container is tilted about said axis, and a thermostatic device for tilting said container,

- said thermostatic device comprising a series of elliptical bimetallic elements having their central portions connected together in succession into a series, the central portion of oneend of said series being connected to the container, substantially as described.

11. In a mercury contactor, the combination of a cylindrical container comprising a central circular insulating section together with end sections of iron connected thereto in gas-tight fashion, trunnions for establishing a pivotal mounting-for the device, conducting wires extending through said trunnions to the interior of the device and establishing connection to the end sections respectively, and a body of mercury within the device, substantially as described.

FRED S. ARMSTRONG. 

